Attic Temperature Differential

The white roof lowered the attic temperature by about 20 f.

Attic temperature differential.

Warner is right that the attic should be close to the outside temp. I have seen duct with r 6 insulation in a vented attic gain 2 3 degrees every 10 feet of run especially if it runs near the peak of the roof. What should the attic temperature be relative to the outside and house temperatures assuming a new supposedly well insulated house. January 8 2010 5 15pm text size.

R value from outdoors to attic 1 u. A good sign is when you open your attic in the winter and you don t see any frost on the nails poking through. Ideal attic temperatures shouldn t be more than 10 to 20 degrees hotter than outside temperatures. Eave space temperature 0 f outdoors calculated difference.

The frost is frozen condensation from the warm air meeting the cold air and not ventilating if that. Heat flow through the insulation is roughly proportional to the temperature differance. After sunset the attic temperatures continue this trend. If you do a good job with attic fans and get the attic temp down to 5f over ambinet 105f then you are dealing with a 27f temperature gradient.

Depending on the location of the ducts and air handling equipment the temperature at the grill and vents may vary a great deal. With 60 f in the eave space on the coldest day there is no risk of pipes freezing and minimal waste heat loss from the heating system ducts. In this situation i check the temp drop at the unit. If the attic surfaces cool down 10f then the energy is 5x as great.

And remember that is with only a 2f degree differential. Your insulating and heating cooling the house not the attic. If your attic soars above 100 degrees and reaches the 150 mark its time to consult professionals. Temperature difference 35 71 41 67 70 0.

That is alot of energy falling on the top of the insulation. Attic temperatures track right at or within a few degrees of outdoor ambient temperatures.